Maleic anhydride-modified resin backbone

ABSTRACT

A resinous material characterized by having a softening point in the range of about 45*C to about 100*C having a basic resin backbone of piperylene and methyl branched monoolefins modified with maleic anhydride and to a method for its preparation. The invention further relates to rubbery copolymers derived from aqueous emulsion polymerization of monomers in the presence of the resinous material of this invention.

United States Patent 11 1 Tazuma et al.

[ Dec. 30, 1975 [54] MALEIC ANHYDRIDE-MODIFIED RESIN BACKBONE [75] Inventors: James J. Tazuma, Stow; Mario D.

Zadra, Barberton, both of Ohio [73] Assignee: The Goodyear Tire & Rubber Company, Akron, Ohio [22] Filed: Sept. 30, 1974 [21] Appl. No.: 510,332

[52] U.S. Cl 260/78.4 D; 260/82.l; 260/879 [51] Int. Cl. C08F 8/46; C08F 236/04 [58] Field of Search 260/78.4 D, 82.1, 82, 879

[56] References Cited UNITED STATES PATENTS 10/1961 Powers 260/78.4 D 3/1971 Van Breen etal 260/78.4 D

Hayashi 260/78.4 D l-lirai et al 260/879 Primary ExaminerJohn Kight, lll Attorney, Agent, or Firm-F. W. Brunner; H. C. Young, Jr.

[57] ABSTRACT tron.

10 Claims, N0 Drawings MALEIC ANHYDRIDE-MODIFIED RESIN BACKBONE This invention relates to a resinous composition and to its method of preparation. This invention particularly relates to the preparation of resins from maleic anhydride and selected hydrocarbon resins derived from piperylene and selected branched monoolefins.

Maleic anhydride can copolymerize with some olefin and diolefin monomers and can also undergo a Diels Alder reaction with some dienes to form adducts.

Some olefins and diolefins can be copolymerized to form useful resins. For example, a unique resin, characterized by having a softening point in the range of about C to about 30C, having a backbone derived from piperylene and 2-methyl-2-butene can be prepared by polymerizing the monomers with boron trifluoride. Such relatively low softening point resins derived from piperylene and selected branched chain monoolefins have been found to have unique utilities in the field of tackifying resins for rubbery materials and particularly in the field of relatively sophisticated pressure sensitive adhesives.

However, such low softening point resins must generally be used as a plasticizing tackifying resin and therefore mixed with other higher softening point tackifiers in order to provide a satisfactory tackifying utility for adhesives and various coatings.

Therefore, it is an object of this invention to provide a higher softening resin with an improved resin composition which can be used, in turn, to provide greater utility.

In accordance with this invention, a resinous material has been discovered which is characterized by having a softening point in the range of about 45C to about 100C preferably about 50C to about 90C, and having a basic resin backbone of piperylene and methyl branched monoolefins which comprises about 50 to about 60 mole percent units derived from piperylene and about to about 30 mole percent units derived from monoolefins selected from at least one methyl branched chain a or B monoolefin containing 4 to 6 carbon atoms, where the mole ratio of piperylene to said branched monoolefin is about 0.8/1 to about 2/1, in combination with about 10 to about 30 mole percent units derived from maleic anhydride, based on the total resin composition. The resinous composition of this invention is required to be prepared by the method which comprises the steps of (A) reacting about 30 to about 60 parts by weight maleic anhydride, or about 10 to about parts by weight maleic anhydride in the presence of an organoperoxide at a temperature in the range of about 150C to about 250C with 100 parts by weight of a hydrocarbon-derived resin having a softening point in the range of about 10C to about 50C prepared by polymerizing in the presence of a catalyst selected from boron trifluoride and boron trifluoride etherate, a monomer mixture which comprises about 40 to about 70 weight percent piperylene, and correspondingly, about 60 to about weight percent of at least one monoolefin selected from methyl branched chain a or ,B monoolefin containing 4 to 6 carbon atoms, where the weight ratio of piperylene to said branched chain monoolefin is about 0.8/1 to about 2.0/1 and (B) removing unreacted maleic anhydride, if any, preferably by distillation.

Therefore, this invention requires a resin having a backbone of piperylene/methyl branched chain monoolefin in combination with units derived from maleic anhydride. Furthermore, the amount of maleic anhydride typically in the resin composition s preparation is substantially reduced by the use of a free radical initiator such as organoperoxides.

Various methyl branched chain monoolefins having a or [3 double bonds can be used. Representative of such monoolefins are isobutylene, 2-methyl-l-butene, 2-methyl-2-butene, Z-methyl-l-pentene and 2-methyl- 2-pentene. The five carbon atom-containing 2-methyll-butene and 2-methyl-2-butene are generally preferred.

The maleic anhydride modification of the hydrocarbonderived resin is preferably facilitated by reacting maleic anhydride with the resin to an extent sufficient to achieve a resinous product having an acid number of about 175 to about 350 after excess maleic anhydride removal. Therefore this acid number range is an important measure, test or indicator of the required extent of maleic anhydride modification.

The modification reaction can be conducted at a temperature in the range of about 150C to about 250C. If a solvent or diluent is used, the temperature of the reaction can be controlled by the boiling point of the solvent selected or carried out high pressure vessel. A generally preferred temperature range is about 180C to about 200C. Typically, the reaction can take about 3 to about 6 hours. The reaction can be conducted at atmospheric pressure or above atmospheric pressure. Also, the reaction can be conducted as a batch process or on a continuous basis. At the conclusion of the reaction, it is generally desired and typically required to remove any excess maleic anhydride usually by distillation, particularly vacuum distillation, or distillation under a reduced pressure, such as from about 5 to about 500, preferably about 10 to about millimeters mercury at a temperature in the range of about C to about C.

It is generally desired that the modification reaction be conducted substantially free of organic solvents or diluents. If a solvent is desired, generally up to about 50 weight percent solvent can be used, although preferably a maximum of about 20 weight percent is allowed based on the total reaction medium or mixture consisting of solvent, maleic anhydride and hydrocarbonderived resin. Representative of various organic solvents are o-dichlorobenzene, decalin, tetralin, diisopropyl benzene, and aromatic solvents boiling in the range of about C to about 200C.

A free radical initiator can be used if desired. If such an initiator is used, usually about 5 to about 15 mole percent is used, based on the said maleic anhydride. Representative of the many various well known free radical initiators are organoperoxides such as di-t-butyl peroxide, di-t-amyl peroxide, t-butyl cumyl peroxide and dicumyl peroxide. Usually, the free radical initiator is added slowly, or incrementally, to the reaction mixture over a period of time, such as about 5 to 180 minutes, in order to maintain control of the reaction. In addition, when an initiator is employed the maleic anhydride to the basic resin backbone weight ratio is typically lowered to about 0.1:] to about 0.25:1.

The hydrocarbon-derived resin necessary for this invention is characterized by a relatively low softening point in the range of about 10C to about 50C, particularly and preferably about 10C to about 40C and is the product of polymerizing in the presence of boron trifluoride or boron trifluoride etherate a mixture which comprises about 40 to about 70 weight percent piperylene, and, correspondingly, about 60 to about 30 weight percent of a branched monoolefin selected from methyl branched tertiary a and B olefins having from 4 to 6 carbon atoms. It is preferred that the monomer mixture to be polymerized comprises from about 45 to about 65 weight percent piperyleneand, correspondingly, about 55 to about 35 weight percent of said methyl branched tertiary monoolefin. Preferably said monoolefin is a methyl branched aolefin containing 5 to 6 carbon atoms. Even more preferably, it is 2-methyl-2-butene.

The basic resin used for this invention, in addition to its characteristic low softening point, may be further characterized by having a viscosity in the range of about 400 to about 1,000,000 and preferably about 1,000 to about 100,000 centipoises (cps) at about C depending somewhat upon the degree of stripping of the resin product to remove light oil-like products and unreacted hydrocarbons. This reference to degree of stripping is not intended to be misleading or ambiguous. Typically, the major portion of the polymerization product is the resin for this invention whereas only a minor portion consists of oil-like products. Reference is made to the degree of stripping only because of the sensitivity of viscosity to very small amounts of low viscosity oil-like products and unreacted hydrocarbons. It is thus desired to strip the product to remove at least about 95 weight percent of such materials. In practice, about 50 to about 85, preferably about 60 to about 80, weight percent of the piperylene/branched olefin mixture is typically converted to the resin.

The characteristic softening point ofthe maleic anhydride modified basic resin backbone product and of the basic resin itself can be determined by ASTM Method E-28-5 8T, which might be modified by first cooling the sample below room temperature and then gradually heating it to the resins softening point, where the softening point is room temperature.

The polymerization reaction for the basic resin is conveniently carried out in the presence of a diluent because it is usually exothermic. Various diluents which are inert in that they do not enter into the polymerization reaction can be used. Representative examples of inert diluents are aliphatic hydrocarbons such as pentane, hexane, and heptane and aromatic hydrocarbons such as toluene and benzene. Unreacted hydrocarbons from the reaction mixture itself can be a diluent. The aliphatic and unreacted hydrocarbons are preferred.

A wide range of temperatures can be used for the polymerization reaction for the preparation of the basic resin such as about -50C to about 50C and preferably in the range of about 0C to about C. The reaction can be carried out at atmospheric or above or below atmospheric pressure. Typically, a satisfactory polymerization can be conducted at atmospheric pressure or at about autogenous pressure developed by the reactants under the operating conditions used. The time of reaction is not particularly of primary importance and can vary from a few minutes to 12 hours or more.

The basic resin backbone polymerizate is typically distilled, by steam distilling for example, to remove light oil-like products, unreacted hydrocarbons and solvent, if used, to yield the product resin.

In the practice of this invention, the catalyst for preparing the basic rcsin backbone is required to be selected from boron trifluoride and a boron trifluoride etherate. The boron trifluoride etherate catalyst used to prepare the resin is a complex'of the type derived from boron trifluoride and an ether having from 2 to about 12, and preferably from 2 to about 6, carbon atoms. The complex is generally represented by the formula:

Representative of various ethers for preparation of the etherate are those having the structure ROR', where R and R are individually selected from saturated alkyl radicals having from 1 to about 6, and preferably from 1 to about 3, carbon atoms, such as methyl, ethyl, npropyl, isopropyl, n-butyl, isobutyl, see-butyl, t-butyl, n-pentyl, isopentyl, t-pentyl, isohexyl, n-hexyl and thexyl radicals. The ethyl radical is usually preferred. The complex, when not available commercially, can generally be prepared by reacting boron trifluoride gas with an ether in about equimolar quantities in an inert atmosphere at a temperature in the range of about 25C to about 25C, and usually in the range of about 10C to about 25C. Representative of various ethers are dimethyl ether, diethyl ether, methyl ethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, diisobutyl ether, di-t-butyl ether, di-n-amyl ether, diisoamyl ether, di-t-amyl ether, ethyl amyl ether, diisohexyl ether, di-n-hexyl ether, di-t-hexyl ether and butyl (2ethylhexyl)ether. Diethyl ether is usually preferred.

Although the maleic anhydride-rnodified basic resin backbone of this invention can be mixed directly as a tackifier with various rubbery materials, it has a unique utility of being able to be incorporated directly into the rubbery molecule, or polymer. For example, a rubber can be prepared by polymerizing monomers to form a latex, with the maleic anhydride-modified resin being utilized in the soap solution for the latex. By this method, the modified resin is incorporated directly into the rubber, thereby having a particularly enhanced value by having the ability to become a part of the rubber itself without migrating or volatilizing when the rubber is exposed to an elevated temperature for a prolonged time.

The importance of this utility is particularly amplified in that the anhydride-modified resin can now totally, or at least substantially, replace the normally required rosin acid soap in the emulsion polymerization medium.

Therefore, in further accordance with this invention, an aqueous emulsion latex-derived copolymer, preferably a rubbery copolymer, can be prepared by free radical polymerizing 100 parts by weight of a mixture comprising about 60 to about weight percent of a diene selected from 1,3-butadiene and isoprene and, correspondingly, about 40 to about 5 weight percent of a comonomer selected from styrene and acrylonitrile, in the presence of about 2 to about 6 weight percent of a soap which comprises about 50 to about weight percent of the sodium or potassium salt of the anhydride modified resin of this invention and correspondingly about 50 to about 0 weight percent ofa sodium or potassium salt of a rosin acid. Such a copolymerization is generally conducted at a temperature in the range of about 40C to about 80C.

The soap solution itself can be prepared by first forming a mixture comprising about. 100 parts by weight of soap, which, in turn, comprises about 50 to about 100 parts by weight of the maleic anhydride modified resin of this invention, and correspondingly, about 50 to more clearly shown in the following Table l. The amounts of materials are listed as parts by weight.

TABLE 1 Experiments A B C D E Basic Resin Piperylene 65 65 65 65 65 lsobutylene 35 2-methyll -butene 35 2methyl-2-butene 35 Z-methyll -pentene 35 2-methyl-2-pentene 35 Solvent [heptane] 50 50 50 50 50 Pzn Temp (C) 30C 30C 30C 30C 30C Basic resin (25C) viscosity (cps) 168,000 80,000 148,000 28,000 148,000 Modified Resin Composition (Maleic Anhydride Product) Maleic Anhydride 23 30 26 26 Basic Hydrocarbon Resin 77 70 80 74 74 Modified Resin Composition Softening point 92C 81C 81C 98C 93C Modified Resin Composition Acid number 268 345 232 294 302 EXAMPLE 11 about 0 parts by weight of rosin acid, and zero to 50 parts by weight of fatty acid, preferably selected from at least one of stearic, oleic and palmitic acid, and about 350 to about 450 parts by weight of water with the corresponding formation of acid of said anhydridemodified resin by hydrolyzation. Then a sufficient parts by weight of sodium hydroxide or potassium hydroxide is about 200 to about 300 parts by weight water is slowly added to achieve a final pH of about 8 to about 1 1.

Upon coagulation of the rubber portion of the latex, the rubbery copolymer is recovered which has the anhydride-modified resin tackifier of this invention attached directly to its molecular network. Thus, the modified resin of this invention functions both as an emulsifying agent for the preparation of the rubbery copolymer and as a tackifying resin for the rubber itself.

The practice of this invention is further illustrated by reference to the following examples which are intended to be representative rather than restrictive of the scope of the invention. Unless otherwise indicated, all parts and percentges are by weight.

EXAMPLE 1 To a series of reactors, identified herein as representing Experiments A-E was charged maleic anhydride, and a basic hydrocarbon resin which had been prepared by polymerizing a mixture comprising piperlyene and various branched chain monoolefins selected from isobutylene, 2-methyl-1-butene, 2-methyl-2-butene, 2-methyl-l-pentene, and 2-methyl-2-pentene in the presence of boron trifluoride. fluoride. The maleic anhydride reactions were allowed to proceed for about 6 hours at about 195C. At this time, excess maleic anhydride was removed from the system under a reduced pressure of about 10 millimeters of mercury at 130C. It was determined that typically about 20 to about weight percent of the maleic anhydride went into the resin. The resin was then recovered by decanting from the reactor. The softening points of the resulting resins were taken according to ASTM E-28-58-T.

The reaction mixture recipes and resulting softening points and acid numbers of the resin compositions are To a reactor equipped with a condenser, stirrer and thermometer was charged 450 parts of a basic resin prepared from piperylene and 2-methyl-2-butene and 294 parts maleic anhydride. The mixture was heated to 190C. The reaction was allowed to proceed for 5 hours and then cooled to about C to about C at which time the unreacted maleic anhydride was flash distilled under a reduced pressure to final condition of about C to about C at about 8 to 10 milliliters mercury. The remaining hot composition was poured into an aluminum dish and allowed to cool. The product was analyzed according to ASTM Method E28-58T to have a softening point of 78C. The product was further analyzed by Goodyear Method AR 505 with sodium hydroxide and determined to have an acid number of about 220 for the hydrolyzed anhydride.

In this example, the piperylene/2-methy1-2-butene resin had been prepared by polymerizing a monomer mixture comprising about 65 parts by weight piperylene and, correspondingly, about 35 parts by weight 2-methyl-2-butene with boron trifluoride. This resulting resin had a softening point of about 20C.

EXAMPLE III A resinous composition was prepared according to the method of Example 11 except that about 98 parts of o-dichlorobenzidene was included in the initial charge to the reactor. The reaction temperature was maintained at reflux of the solvent or about C to about 184C. The softening point of the resulting resin composition was determined to be about 70C and its acid number was determined to be about 220.

EXAMPLE IV To a 1-liter, 3-neck, flask, equipped with a condenser, stirrer and thermometer was charged 475 grams (1 mole) of a hydrocarbon-derived resin and 98.1 grams (1 mole) maleic anhydride. Said hydrocarbon-derived resin had been previously prepared by polymerizing a mixture comprising piperylene and 2- methyI-Z-butene, where the mole ratio of piperylene to 2-methyl-2-butene was about 1.221, in the presence of boron trifluoride. Such resin had a softening point in the range of about 18C to about 25C. The mixture was heated to a temperature of about 175C to about 180C and 14.6 grams (0.1 mole) di-t-butyl peroxide was slowly and continuously added over a period of about 30 minutes. After stirring the mixture for an additional two hours, a vacuum stripper was attached to the flask and the decomposition products of the di-t-butyl peroxide and any unreacted maleic anhydride was removed under reduced pressure. Actually, very little maleic anhydride was removed. The final conditions of removal were a temperature of about 175C to about 180C and a reduced pressure of about to about milliliters of mercury. The remaining hot product was simply poured from the flask into an aluminum dish and allowed to cool.

The cooled product was an amber solid having a Gardner color of 11 and a softening point of about 67C. Its acid number, according to Method AR 505, was determined to be about 175.

EXAMPLE V A 15 percent soap solution of the maleic anhydridemodified basic hydrocarbon-derived resin backbone of Example IV was prepared. The preparation involved mixing 573 grams of said-anhydride-modified resin, 2,700 grams hot water and 29.6 grams of a potassium soap of fatty acids such as stearic acid, oleic acid and palmitic acid at 75C to 95C. Then, 96.3 grams of potassium hydroxide in 880 grams water was slowly addeggover a period of about 15 to about minutes. The ixture was maintained at about 90C to about 95C and stirring continued for about 3 to about 4 hours. A soap solution resulted having a final pH of about 10.

EXAMPLE VI A batch of aqueous latex was prepared in conventional manner by polymerizing 100 parts ofa monomer mixture comprising 25 parts styrene and 75 parts 1,3- butadiene in the presence of a redox initiator system at 50C using 4.5 parts of soap as prepared in Example V. The monomers were copolymerized to a 60 percent conversion, following which the latex was steam stripped and the resulting copolymer acid coagulated, washed and oven dried at about 82C. A sheet of the rubbery copolymer was visually determined to have better building tack, as its ability to stick to itself, than a similar control sample of copolymer prepared with a soap solution containing rosin acid soap instead of the potassium salt of the anhydride-modified resin of this invention.

EXAMPLE Vll A batch of latex was prepared according to the method of Example VI, except that the soap consisted of a 50/50 mixture of the potassium salt of a fatty acid as a mixture of stearic, oleic and palmitic acids and the potassium salt of the maleic anhydride-modified resin of this invention. A stable coagulum-free latex was obtained from which the copolymer was coagulated, washed and oven dried.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed is:

l. A resinous material characterized by having a softening point in the range of about 45C to about C having a basic resin backbone of piperylene and methyl branched monoolefins which comprises about 50 to about 60 mole percent units derived from piperyl ene and about 20 to about 30 mole percent units derived from monoolefins selected from at least one methyl branched chain a or B monoolefin containing 4 to 6 carbon atoms, where the mole ratio of piperylene to said branched monoolefin is about 0.8/1 to about 2/1, in combination with about 10 to about 30 mole percent units derived from maleic anhydride, based on the total resin composition.

2. The resinous composition of claim 1 prepared by the method which comprises the steps of (A) reacting about 30 to about 60 parts by weight maleic anhydride, or about 10 to about 25 parts by weight maleic anhydride in the presence of an organoperoxide at a temperature in the range of about C to about 250C with 100 parts by weight of a hydrocarbon-derived resin having a softening point in the range of about 10C to about 50C prepared by polymerizing in the presence of a catalyst selected from boron trifluoride and boron trifluoride etherate, a monomer mixture which comprises about 40 to about 70 weight percent piperylene, and correspondingly, about 60 to about 30 weight percent of at least one monoolefin selected from methyl branched chain a or B monoolefin containing 4 to 6 carbon atoms, where the weight ratio of piperylene to said branched chain monoolefin is about 0.8/1 to about 2.0/1 and (B) removing unreacted maleic anhydride, if any, by distillltion.

3. The resinous composition of claim 2 where said branched chain monoolefms are selected from isobutylene, 2-methyl-l-butene, 2-methyl-2-butene, Z-methyl- 1 -pentene and Z-methyl-Z-pentene.

4. The resinous composition of claim 2 where maleic anhydride is reacted with said resin to an extent sufficient to achieve a resinous product having an acid number of about to about 350 after excess maleic anhydride removal.

5. The resinous composition of claim 2 prepared by reacting maleic anhydride with said basic resin backbone in the presence of a free radical initiator selected from di-t-butyl peroxide, di-t-amyl peroxide, tbutyl cumyl peroxide and dicumyl peroxide.

6. The resinous composition of claim 5 where the weight ratio of maleic anhydride to the basic resin backbone is about 01/1 to about 0.25/1.

7. The resinous composition of claim 2 where said boron trifluoride etherate is a complex derived from boron trifluoride and an ether selected from dimethyl ether, diethyl ether, methyl ethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, diisobutyl ether, di-t-butyl ether, di-n-amyl ether, diisoamyl ether, di-t-amyl ether, ethyl amyl ether, diisohexyl ether, di-nhexyl ether, di-t-hexyl ether and butyl (2ethylhexyl)ether.

8. An anhydride-modified resin acid prepared by water-hydrolyzing said anhydride-modified resin backbone of claim 2.

9. The resinous composition of claim 2 prepared by reacting 30 to 60 parts by weight maleic anhydride at a temperature in the range of about 150C to about 250C with 100 parts by weight of said hydrocarbonderived resin having a softening point in the range of about 10C to about 50C.

10 percent piperylene and, correspondingly, about 60 to about 30 weight percent of a methyl branched chain monoolefin containing 5 to 6 carbon atoms, primarily consisting of Z-methyI-Z-butene, and removing any excess maleic anhydride by distillation. 

1. A RESINOUS MATERIAL CHARACTERIZED BY HAVING A SOFTENING POINT IN THE RANGE OF ABOUT 45*C TO ABOUT 100*C HAVING A BASIC RESIN BACKBONE OF PIPERYLENE AND METHYL BRANCHED MONOOLEFINS WHICH COMPRISES ABOUT 50 TO ABOUT 60 MOLE PERCENT UNITS DERIVED FROM PIPERYLENE AND ABOUT 20 TO ABOUT 30 MOLE PERCENTS UNITS DERIVED FROM MOONOLEFINS SELECTED FROM AT LEAST ONE METHYL BRANCHED CHAIN A OR B MONOOLEFIN CONTAINING 4 TO 6 CARBON ATOMS, WHERE THE MOLE RATIO OF PIPERYLENE TO SAID BRANCHED MONOOLEFIN IS ABOUT 0.8/1 TO ABOUT 2/1, IN COMBINATION WITH ABOUT 10 TO ABOUT 30 MOLE PERCENT UNITS DERIVED FROM MALEIC ANHYDRIDE, BASED ON THE TOTAL RESIN COMPOSITION.
 2. THE RESINOUS COMPOSITION OF CLAIM 1 PREPARED BY THE METHOD WHICH COMPRISES THE STEPS OF (A) REACTING ABOUT 30 TO ABOUT 60 PARTS BY WEIGHT MALEIC ANHYDRIDE, OR ABOUT 10 TO ABOUT 25 PARTS BY WEIGHT MALEIC ANHYDRIDE IN THE PRESENCE OF AN ORGANOPEROXIDE AT A TEMPERATURE IN THE RANGE OF ABOUT 150*C TO ABOUT 250*C WITH 100 PARTS BY WEIGHT OF A HYDROCARBON-DERIVED RESIN HAVING A SOFTENING POINT IN THE ANGE OF ABOUT 10*C TO ABOUT 50*C PREPARED BY POLYMERIZING IN THE PRESENCE OF A CATALYST SELECTED FROM BORON TRIFLUORIDE AND BORON TRIFLUORIDE ETHERATE, A MONOMER MIXTURE WHICH COMPRISES ABOUT 40 TO ABOUT 70 WEIGHT PERCENT PIPERYLENE, AND CORRESPONDINGLY, ABOUT 60 TO ABOUT 30 WEIGHT PERCENT OF AT LEAST ONE MONOOLEFIN SELECTED FROM METHYL BRANCHED CHAIN A OR B MONOOLEFIN CONTAINING 4 TO 6 CARBON ATOMS, WHERE THE WEIGHT RATIO OF PIPERYLENE TO SAID BRANCHED CHAIN MONOOLEFIN IS ABOUT 0.8/1 TO ABOUT 2.0/1 AND (B) REMOVING UNREACTED MALEIC ANHYDRIDE, IF ANY, BY DISTILLATION.
 3. The resinous composition of claim 2 where said branched chain monoolefins are selected from isobutylene, 2-methyl-1-butene, 2-methyl-2-butene, 2-methyl-1-pentene and 2-methyl-2-pentene.
 4. The resinous composition of claim 2 where maleic anhydride is reacted with said resin to an extent sufficient to achieve a resinous product having an acid number of about 175 to about 350 after excess maleic anhydride removal.
 5. The resinous composition of claim 2 prepared by reacting maleic anhydride with said basic resin backbone in the presence of a free radical initiator selected from di-t-butyl peroxide, di-t-amyl peroxide, t-butyl cumyl peroxide and dicumyl peroxide.
 6. The resinous composition of claim 5 where the weight ratio of maleic anhydride to the basic resin backbone is about 0.1/1 to about 0.25/1.
 7. The resinous composition of claim 2 where said boron trifluoride etherate is a complex derived from boron trifluoride and an ether selected from dimethyl ether, diethyl ether, methyl ethyl ether, di-n-propyl ether, diisopropyl ether, di-n-buTyl ether, diisobutyl ether, di-t-butyl ether, di-n-amyl ether, diisoamyl ether, di-t-amyl ether, ethyl amyl ether, diisohexyl ether, di-n-hexyl ether, di-t-hexyl ether and butyl (2ethylhexyl)ether.
 8. An anhydride-modified resin acid prepared by water-hydrolyzing said anhydride-modified resin backbone of claim
 2. 9. The resinous composition of claim 2 prepared by reacting 30 to 60 parts by weight maleic anhydride at a temperature in the range of about 150*C to about 250*C with 100 parts by weight of said hydrocarbon-derived resin having a softening point in the range of about 10*C to about 50*C.
 10. The resinous composition of claim 9 prepared by reacting said maleic anhydride with said hydrocarbon-derived resin having a softening point in the range of about 10*C to about 50*C, itself prepared by polymerizing in the presence of boron trifluoride a monomer mixture which comprises about 40 to about 70 weight percent piperylene and, correspondingly, about 60 to about 30 weight percent of a methyl branched chain monoolefin containing 5 to 6 carbon atoms, primarily consisting of 2-methyl-2-butene, and removing any excess maleic anhydride by distillation. 